Announcing our new "CLUBS" section where you can join or create a Rivian club or group! You can use this new feature to conveniently plan and discuss local events, gatherings or other club/group related topics.
So we encourage you to join (or start) special-interest and regional-based Rivian clubs at: https://www.rivianforums.com/forum/group-categories/clubs-groups.1/
Guess you don't have WestPenn Power. As of June 1st WPP base rate went from 0.05667/kwh to .08198/kwh. There are also additional distribution and service support charges that add an additional .044931/kwh. Not sure if those additional charges changed on June 1, but if not then the total cost in SW PA for WPP is .126911/kwh. Plus $7.83/month in fixed charges.
In Orange County, CA I have a 6.29 kw system that went live August 16th last year, in just under 10 months it has generated 8.1 MWh.
Amazing!!!!
I made 54kW today in AZ. 8kW Tesla system, South facing.
That's about 27 kWh/d which would be over 2 hours full sun equivalent (hFSE) with my 13 kw system. I'm sure you are better off in AZ than I am in VA but I only average about 3.5 hFSE/da in December here in VA but it appears it is doable (with a 13 kW system).
I'm utilizing a combination of panel production and battery supply from the Powerwalls, so I can utilize the full 11kW charge rate for the truck. Once my batteries reach approximately 8O% (or more) if I'm home I'll plug the the truck in. By that time of the day right now I'd be producing about 7.3kWh on the panels. 7kWh coming off of solar and the remaining from the batteries.
. For now it's fun. We like being off grid in suburbia. 
My standard tip for people using Powerwalls and PV is to NOT take anything from the Powerwalls to charge the BEV if you can avoid it. Using your numbers you would dial the charging rate back to 7 kW if you have 7 kW solar left over after all other loads are accounted for. In this way the entire excess solar production goes to the car batteries - not the Powerwalls and the BEV charge is NOT subject to round trip losses, Note that Tesla claims these are 10% but in reality they are more like 20 - 30% (depending on loads).
Rivian charge controller won't adjust feed rate automatically to a lower requested charge rate. You'd have to flip dip switches to accomplish this twice per day. Your idea above would be ideal, but the losses don't really factor in monetarily for me when I can remain almost 100% off grid while using the BEV system. Your idea is ideal though.
No, no automation so if you really want to follow the sun you have to maually adjust the charge rate with the app which gets old fast. What I am able to do and get quite close to the ideal is to schedule the charge (at, e.g., 09:30) at a rate (e.g. 8.5 kW) that is a little ave what you expect the production to be (e.g. 8 kW) at the start time. When the charge starts you are in the red for a while but fairly quickly get into the green as the sun rises, This doesn't work very well on cloudy/rainy days but you can always adjust on those days if you want to.
In the desert summers we fully charge and nearly discharge every single day, so either way we're cycling from full to nearly empty, so until then it makes sense to utilize the fueling capacity to it's highest levels. My concern isn't battery cycles of charge and discharge with this PV/BEV system. The goal is absolute useability of the entire production and storage capacity. In 8 years I'll reevaluate with panel and battery efficiencies increasing dramatically. It makes little sense to me to handicap production for 8 years based upon battery degradation challenges from cycling.
